High power transistor and diode semiconductor die configured for direct mounting on a substrate typically include terminal pads on both major faces. For example, a power field effect transistor (FET) has its source and gate terminals formed on one face, and its drain terminal formed on the opposite face. The terminals on one face of the die interface directly with conductors formed on the surface of a substrate on which the die is mounted, and the terminal(s) on the exposed face of the die can be coupled to other substrate conductors by wire bonding. However, the wire bonds interfere with top-side cooling of the die, effectively limiting the power dissipation of the device. The U.S. Pat. No. 6,873,043 discloses an improved arrangement in which a heat conducting laminate structure couples terminal(s) on the exposed face of the die to substrate conductors and at the same time thermally couples the die to a top-side heatsink for improved heat dissipation.